Heat exchanger

ABSTRACT

The invention relates to a heat exchanger comprising one tube, and preferably a plurality of tubes, which extend through a heat-exchange chamber starting from a tube sheet, wherein the tube sheet is made of a fiber-reinforced plastics material. The invention further relates to a method for producing a heat exchanger of this kind and to the use of a heat exchanger of this kind.

The invention relates to a heat exchanger comprising one tube, and preferably a plurality of tubes, which extend through a heat-exchange chamber starting from a tube sheet. The invention further relates to a method for producing a heat exchanger of this kind and to the use of a heat exchanger of this kind.

Shell and tube heat exchangers are known from the prior art. They comprise a plurality of tubes which extend through a typically cylindrical heat-exchange chamber. A first fluid is guided within the tubes and these tubes are flushed with a second fluid in the heat-exchange chamber. Heat exchange takes place in this process. At the ends, the tubes are typically set into tube sheets, which are usually made of metal materials in known heat exchangers of this kind. In order to design the heat exchangers for use with corrosive media, non-metal materials, such as graphite, have also already been used in the prior art to produce tube sheets.

The object of the invention is to provide a design of generic heat exchangers that is suitable for use with corrosive media and satisfies high mechanical requirements.

This object is achieved according to the invention by a heat exchanger comprising one tube, and preferably a plurality of tubes, which extend through a heat-exchange chamber starting from a tube sheet, wherein the tube sheet is made of a fiber-reinforced plastics material. Preferably, the heat exchanger according to the invention is a shell and tube heat exchanger that comprises a plurality of tubes.

In an embodiment, it is provided that the tubes extend through the heat-exchange chamber between two tube sheets positioned at opposite ends of the heat-exchange chamber, wherein it is preferably provided that the two tube sheets are made of a fiber-reinforced plastics material.

The tube sheet(s) are preferably planar. They have at least the required size for receiving a tube, but may also have extensions of several meters and receive several hundred tubes. The tube sheets are dimensioned on the basis of the pressures and temperatures for which the heat exchanger is designed. The tubes preferably have a round cross section. The cross-sectional areas depend on the design of the heat exchanger. Typical tube diameters range from a few millimeters to approximately 50 mm.

In an embodiment, it is provided that the heat-exchange chamber is tubular and is enclosed by an axially extending shell between the two tube sheets. The heat-exchange chamber may be round or oval in cross section. Accordingly, the tube sheets may be present as round or oval plates and the shell may be round or oval in cross section.

In an embodiment, it is provided that covers are fitted to the outer sides of the tube sheets facing away from the heat-exchange chamber in order to form forward-flow-side and return-flow-side distributor chambers for a first heat-exchange medium that is intended to flow through the tubes.

In an embodiment, it is provided that the shell surface comprises an inlet and an outlet for a second heat-exchange medium. The inlet and outlet are preferably arranged in opposite end regions of the heat-exchange chamber, i.e. close to the tube sheets, in order to make it possible for the second heat-exchange medium to flow through the heat-exchange chamber as completely as possible and for the tubes to therefore be flushed with said medium.

In an embodiment, it is provided that the fiber reinforcement of the fiber-reinforced plastics material comprises or consists of carbon fibers and/or in that the fibers are present as a woven fabric in the fiber reinforcement of the fiber-reinforced plastics material. Woven fabrics are produced by weaving together continuous fibers, for example rovings. As a result, particularly favorable mechanical properties can be obtained.

In an embodiment, it is provided that the matrix material of the fiber-reinforced plastics material comprises or consists of phenolic resin.

In an embodiment, it is provided that the tube sheet(s) preferably comprise(s) sleeve-shaped tube receptacles for receiving the tube ends. For example, holes can be made in the tube sheets, into or through which the tube receptacles and tube ends are inserted.

In an embodiment, it is provided that the tube sheet(s) is/are made of a plurality individual components, the tube sheet(s) preferably comprising perforated base plates and cover plates, on which sleeve-shaped tube receptacles are retained.

For example, it may be provided that the tube sheet comprises a base plate, a cover plate, and filler segments enclosed in a sandwich-like manner between these plates. The base plate and the cover plate may be perforated. The tube receptacles may be provided with flanges and the flanges may be enclosed in the space between the plates. The sleeve-shaped part of the tube receptacles may project beyond the base plate into the heat-exchange space. The filler segments stabilize the thus constructed tube sheet.

In an embodiment, the diameter of the cover plate is greater than the diameter of the base plate. Therefore, in the context of producing the heat exchanger, the tubes can be inserted into the tube receptacles, the composite construction thus produced can then be guided through the heat-exchange space, and lastly the cover plates can be fitted.

Alternatively, a configuration is of course also conceivable in which both the base plate and the cover plate have a diameter that is greater than the internal diameter of the shell tube. It is also conceivable for U-shaped tubes to be inserted into the tube sheet.

The individual components of the tube sheets can be prefabricated in molds and can then be connected to one another and to the tubes. All the components as well as the tube may be made of the same material, for example of a phenolic-resin material reinforced with a woven carbon-fiber material. The connection can be made by adhesion or welding, and is preferably an integral connection.

In an embodiment, alternatively or additionally to mechanically enclosing the tube ends in the tube sheets, tubes and tube sheets can be connected by a preferably integral connection, which can be obtained by adhesion or welding, for example.

For example, in order to obtain an integral connection, a cement made of the same material as the tube sheets, tube sheet components and/or tubes can be used, for example a phenolic-resin/graphite cement can be used, which is heated. A thus obtained, integrally produced composite construction of tubes and tube sheet does not have any points of weakness and is suitable for high pressure and temperature shock stress, as can occur in evaporation applications, for example.

In the context of the production of a heat exchanger according to the invention, as is likewise covered by the invention, it may be provided that the tubes and tube sheet are joined together and are then preferably integrally interconnected. It is preferably provided that the tubes are inserted into the receptacles, and therefore the tubes and the tube sheet, and optionally the components of the tube sheet where applicable, are preferably integrally connected to one another.

In an embodiment, the base plate is reinforced in the region of the tube receptacles. Therefore, the construction can better withstand the action of axial forces on the tubes. A seal can also be inserted in the boundary region between the tube and tube sheet, for example between the inside of the base plate or the inside of the cover plate and the tube flange. Therefore, in the case of a non-integral connection, the fluid spaces can be reliably sealed from one another.

The invention further relates to the use of a heat exchanger according to the invention. The heat exchanger can be used in this case for heating or cooling corrosive fluids or for evaporating liquids, in particular corrosive liquids such as acids, for example. The heat exchanger can be operated under pressure in this case, such that at least one of the heat-exchange media is forced into the tubes or the heat-exchange chamber under increased pressure of greater than 2 bar, greater than 5 bar, greater than 10 bar or greater than 50 bar, for example. Alternatively, at least one of the heat-exchange media can also be conducted into the tubes or heat-exchange chamber in an unpressurised manner or at a negative pressure.

Further features and advantages of the invention are found in the embodiment explained with reference to the drawings, in which:

FIG. 1 is a longitudinal section through a shell and tube heat exchanger from the prior art; and

FIG. 2 is a section through a tube sheet of a shell and tube heat exchanger according to the invention.

FIG. 1 shows a shell and tube heat exchanger 1 from the prior art. As main components, it comprises a plurality of tubes 2 that are circular in cross section and extend through a circular cylindrical heat-exchange chamber 4 in the axial direction between two planar and circular tube sheets 3. The heat-exchange chamber 4 is delimited laterally by a shell tube 5 that is circular in cross section. Covers 6 are fitted to the outer sides of the tube sheets 3 facing away from the heat-exchange chamber 4 in order to form distributor chambers 7 for a first heat-exchange medium on the forward-flow and return-flow sides of the tubes 2. An inlet 8 and an outlet 9 for a second heat-exchange medium is located in the regions of the shell tube 5 close to the edge. This structure, which is known from the prior art in principle, can also be used in shell and tube heat exchangers according to the invention.

At least one of the tube sheets 3 can be formed in a shell and tube heat exchanger 1 according to the invention as shown in FIG. 2.

This tube sheet 3 comprises four essential parts, namely a base plate 31, a cover plate 33, filler segments 32 enclosed in a sandwich-like manner between these plates 31 and 33 for stabilization, as well as sleeve-shaped tube receptacles 34. The base plate 31 and the cover plate 33 are each perforated, the holes 31 a in the base plate 31 and the holes 33 a in the cover plate 33 being arranged so as to be aligned and the holes 31 a in the base plate 31 having a slightly larger diameter than the holes 33 a in the cover plate 33. Specifically, the diameter of the holes 31 a in the base plate 31 corresponds to the external diameter of the tube receptacles 34 and the diameter of the holes 33 a in the cover plate 33 corresponds to the internal diameter of the tube receptacles 34.

The base plate 31, the intermediate segments 32, the cover plate 33, and the tube receptacles 34 are each made of a phenolic-resin material reinforced with a woven carbon-fiber material. The tubes 2 can be made of the same material and are inserted into the tube receptacles 35 projecting from the base plate 31.

The tube receptacles 34 are provided with flanges 35, which are enclosed in the space between the plates 31 and 33. The filler segments 32 fill the regions of the space between the plates 31 and 33 that are not filled by the flanges 35. The flange 35 is thus clamped between the base plate 31 and the cover plate 33.

The components 31-34 of the tube sheet 3 and the tubes 2 are integrally connected, wherein this integral connection is obtained by applying a carbon-fiber/phenolic-resin cement and then heating it.

The diameter of the cover plate 33 is greater than the diameter of the base plate 31. Therefore, in the context of producing the shell and tube heat exchanger 1, the tubes 2 can first be inserted into the tube receptacles 34 fixed to the base plate 31, this composite construction with the inserted tubes 2 can then be guided through the shell tube 5, and lastly the cover plate 33 can be fitted. 

1. Heat exchanger comprising one tube, and preferably a plurality of tubes, which extend through a heat-exchange chamber starting from a tube sheet, wherein the tube sheet is made of a fiber-reinforced plastics material.
 2. Heat exchanger according to claim 1, wherein the tubes extend through the heat-exchange chamber between two tube sheets positioned at opposite ends of the heat-exchange chamber, and preferably the two tube sheets are made of a fiber-reinforced plastics material.
 3. Heat exchanger according to claim 2, wherein the heat-exchange chamber is tubular and is enclosed by an axially extending shell between the two tube sheets.
 4. Heat exchanger according to claim 1, wherein the fiber reinforcement of the fiber-reinforced plastics material comprises or consists of carbon fibers and/or the fibers are present as a woven fabric in the fiber reinforcement of the fiber-reinforced plastics material.
 5. Heat exchanger according to claim 1, wherein the matrix material of the fiber-reinforced plastics material comprises phenolic resin.
 6. Heat exchanger according to claim 1, wherein the tube sheet(s) preferably comprise(s) sleeve-shaped tube receptacles for receiving the tube ends.
 7. Heat exchanger according to claim 1, wherein the tube sheet(s) is/are made of a plurality individual components, and preferably comprise perforated base plates and cover plates, on which sleeve-shaped tube receptacles are retained.
 8. Method for producing a heat exchanger according to claim 1, wherein the tubes and tube sheet are joined together and are then preferably integrally interconnected.
 9. A method for heating or cooling corrosive fluids, comprising using the heat exchanger of claim
 1. 10. A method for evaporating liquids, in particular corrosive liquids such as acids, for example, comprising using the heat exchanger of claim
 1. 11. Heat exchanger according to claim 3, wherein the fiber reinforcement of the fiber-reinforced plastics material comprises carbon fibers and/or the fibers are present as a woven fabric in the fiber reinforcement of the fiber-reinforced plastics material.
 12. Heat exchanger according to claim 2, wherein the fiber reinforcement of the fiber-reinforced plastics material comprises carbon fibers and/or the fibers are present as a woven fabric in the fiber reinforcement of the fiber-reinforced plastics material.
 13. Heat exchanger according to claim 12, wherein the matrix material of the fiber-reinforced plastics material comprises phenolic resin.
 14. Heat exchanger according to claim 11, wherein the matrix material of the fiber-reinforced plastics material comprises phenolic resin.
 15. Heat exchanger according to claim 4, wherein the matrix material of the fiber-reinforced plastics material comprises phenolic resin.
 16. Heat exchanger according to claim 3, wherein the matrix material of the fiber-reinforced plastics material comprises phenolic resin.
 17. Heat exchanger according to claim 2, wherein the matrix material of the fiber-reinforced plastics material comprises phenolic resin.
 18. Heat exchanger according to claim 13, wherein the tube sheet(s) comprise(s) sleeve-shaped tube receptacles for receiving the tube ends.
 19. Heat exchanger according to claim 14, wherein the tube sheet(s) comprise(s) sleeve-shaped tube receptacles for receiving the tube ends.
 20. Heat exchanger according to claim 15, wherein the tube sheet(s) comprise(s) sleeve-shaped tube receptacles for receiving the tube ends. 